ST92150CV1Q-Auto STMicroelectronics, ST92150CV1Q-Auto Datasheet - Page 309

• Manufacturer Part Number: ST92150CV1Q-Auto
• Description: 8-bit MCU for automotive
• Manufacturer: STMicroelectronics

Specifications of ST92150CV1Q-Auto

• Internal Memory: Single Voltage FLASH up to 256 Kbytes, RAM up to 8Kbytes, 1K byte E3 TM (Emulated EEPROM)
• Minimum Instruction Time: 83 ns (24 MHz int. clock)

J1850 BYTE LEVEL PROTOCOL DECODER (Cont’d)
MSG+CRC, Message byte then append CRC op-
code.
The ‘Message byte with CRC’ opcode is set when
the user program wants to transmit a single byte
message followed by a CRC byte, or transmit the
final byte of a message string followed by a CRC
byte.
A single byte message is basically an SOF symbol
followed by a single data byte retrieved from TX-
DATA register followed by the computed CRC
byte followed by an EOD symbol. If the J1850 bus
is in idle condition when the opcode is written, an
SOF symbol is immediately transmitted out the
VPWO pin. It then transmits the byte contained in
the TXDATA register, then the computed CRC
byte is transmitted. VPWO is then set to a passive
state. If the J1850 bus is not idle and the J1850
transmitter has not been locked out by loss of arbi-
tration, then the TXDATA byte is transferred to the
serial output shift register for transmission immedi-
ately on completion of any previously transmitted
data. After completion of the TXDATA byte the
computed CRC byte is transferred out the VPWO
pin and then the VPWO pin is set passive to time
an EOD symbol.
Special Conditions for MSG+CRC Transmit:
– 1) A MSG+CRC opcode cannot be queued on
– 2) If NFL=0, a MSG+CRC can only be queued if
Caution should be taken when TRA gets set in
these cases because the TDUF error sequence
may engage before the user program has a
top of an executing IFR3 opcode. If so, then
TRA is set, and TDUF will get set because the
transmit state machine will be expecting more
data, then the inverted CRC is appended to this
frame. Also, no message byte will be sent on
the next frame.
Received Byte Count for this frame <=10 other-
wise the TRA will get set, and TDUF will get set
because the state machine will be expecting
more data, so the transmit machine will send
the inverted CRC after the byte which is pres-
ently transmitting. Also, no message byte will be
sent on the next frame.
ST92124xxx-Auto/150xxxxx-Auto/250xxxx-Auto
chance to rewrite the TXOP register with the cor-
rect opcode. If a TDUF error occurs, a subsequent
MSG+CRC write to the TXOP register will be used
as the first byte of the next frame.
IFR1, In-Frame Response Type 1 opcode.
The In-frame Response Type 1 (IFR 1) opcode is
written if the user program wants to transmit a
physical address byte (contained in the PADDR
register) in response to a message that is currently
being received.
The user program decides to set up an IFR1 upon
receiving a certain portion of the data byte string of
an incoming message. No write of the TXDATA
register is required. The IFR1 gets its data byte
from the PADDR register.
The JBLPD block will enable the transmission of
the IFR1 on these conditions:
– 1) The CRC check is valid (otherwise the CRCE
– 2) The received message length is valid if ena-
– 3) A valid EOD minimum symbol is received (oth-
– 4) If NFL = 0 & Received Byte Count for this
– 5) If not presently executing an MSG, IFR3, op-
– 6) If not presently executing an IFR1, IFR2, or
– 7) If not presently receiving an IFR portion of a
The IFR1 byte is then attempted according to the
procedure described in section “Transmitting a
type 1 IFR”. Note that if an IFR1 opcode is written,
a queued MSG or MSG+CRC is overridden by the
IFR1.
is set)
bled (otherwise the TRA is set)
erwise the IFD may eventually get set due to
byte synchronization errors)
frame <=11 (otherwise TRA is set)
code (otherwise TRA is set, and TDUF will get
set because the transmit state machine will be
expecting more data, so the inverted CRC will
be appended to this frame)
IFR3+CRC opcode otherwise TRA is set (but no
TDUF)
frame, otherwise TRA is set.
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